Update pip to 19.0.2

[pyup-bot]

This PR updates pip from 19.0.1 to 19.0.2.

Changelog

19.0.2

===================

Bug Fixes
---------

- Fix a crash where PEP 517-based builds using ``--no-cache-dir`` would fail in
some circumstances with an ``AssertionError`` due to not finalizing a build
directory internally. (`6197 <https://github.com/pypa/pip/issues/6197>`_)
- Provide a better error message if attempting an editable install of a
directory with a ``pyproject.toml`` but no ``setup.py``. (`6170 <https://github.com/pypa/pip/issues/6170>`_)
- The implicit default backend used for projects that provide a ``pyproject.toml``
file without explicitly specifying ``build-backend`` now behaves more like direct
execution of ``setup.py``, and hence should restore compatibility with projects
that were unable to be installed with ``pip`` 19.0. This raised the minimum
required version of ``setuptools`` for such builds to 40.8.0. (`6163 <https://github.com/pypa/pip/issues/6163>`_)
- Allow ``RECORD`` lines with more than three elements, and display a warning. (`6165 <https://github.com/pypa/pip/issues/6165>`_)
- ``AdjacentTempDirectory`` fails on unwritable directory instead of locking up the uninstall command. (`6169 <https://github.com/pypa/pip/issues/6169>`_)
- Make failed uninstalls roll back more reliably and better at avoiding naming conflicts. (`6194 <https://github.com/pypa/pip/issues/6194>`_)
- Ensure the correct wheel file is copied when building PEP 517 distribution is built. (`6196 <https://github.com/pypa/pip/issues/6196>`_)
- The Python 2 end of life warning now only shows on CPython, which is the
implementation that has announced end of life plans. (`6207 <https://github.com/pypa/pip/issues/6207>`_)

Improved Documentation
----------------------

- Re-write README and documentation index (`5815 <https://github.com/pypa/pip/issues/5815>`_)

Links

• PyPI: https://pypi.org/project/pip
• Changelog: https://pyup.io/changelogs/pip/
• Homepage: https://pip.pypa.io/